Recent developments in cooking large pieces of meat, such as whole fowl, large cuts of beef or pork, and so on, have centered on the use of radiant heat, such as described in U.S. Patent Publication No. 2008/0121117, to Best, for a Radiant Tube Broiler. Best teaches the use of a removable emitter tube, the interior of which forms a first cavity (i.e., a cooking cavity) wherein the food item is positioned and cooked. The emitter tube must be placed inside an outer tube to thereby form a second cavity (i.e., a heating cavity) between the interior wall of the outer tube and the exterior wall of the inner tube. In this “double cavity” system, a heating unit delivers hot combustion gas into the bottom of the outer heating cavity in order to heat the outer surface of the emitter tube. This heat must then be conducted through the wall of the emitter tube to the inner surface of the tube so that infrared radiation is then emitted from the inner surface for cooking the food inside the emitter tube (i.e., the inside cooking cavity). An actual product, Char-Broil's The Big Easy®, has been made, marketed, and sold using this technology and successfully cooks large pieces of meat effectively.
As is typically the case, however, further developments, advancements, and modifications in radiant tube broiler technology would be very desirable for improving upon the structure, operation, weight, efficiency, and/or cost of the prior art system described above. For example, in the existing double cavity system, a significant amount of warm-up time is needed for the heating system to bring food to cooking temperature because the emitter tube acts as a thermal barrier. Tests were conducted on a Char-Broil The Big Easy® double cavity apparatus showing that it took 16 minutes after start-up of the prior art double cavity apparatus to reach a stable air temperature and radiant wall temperature within the emitter tube (i.e., a point of thermal equilibrium). The radiant heat flux within the cooking cavity of the emitter tube at the point of thermal equilibrium was 4.3 KW/m2 with an exhaust gas temperature of 770° F.
Also, the double cavity construction of the prior system is heavy, making portability of a turkey-sized unit difficult.
In addition, in the prior double cavity system, because of the temperature to which the removable emitter tube is exposed as a result of (a) the nature of the heating chamber surrounding the tube, (b) the necessity of conducting heat through the wall of the emitter tube, and (c) the need to angle the burner flame toward the emitter, it has been necessary to form the emitter tube from stainless steel or other heavy materials having a comparable degree of heat resistance. Again, tests conducted on a prior art double cavity Char-Broil The Big Easy® apparatus showed that, at the point of thermal equilibrium discussed above, the removable emitter tube reached a temperature of close to 800° F. At a temperature of this magnitude, the coating of aluminum on an aluminized steel structure begins to fail and loses its ability to protect the steel from corrosion. Consequently, in the prior art double cavity apparatus it has been necessary to form the removable emitter tube from stainless steel or a similar heat resistant material such as porcelanized steel. Stainless steel has been the material preferred for use in forming the emitter tube because porcelanized steel, which is also more expensive than aluminized steel, is susceptible to chipping damage.
In addition to the cost inherent in the use of stainless steel, the weight of a double cavity radiant tube broiler having a stainless steel emitter tube sized for cooking a 25 lb. turkey will typically be about 31 lbs. Moreover, the weight of the stainless steel emitter tube alone is about 5 lbs.